def std_deviation(list_of_numbers):
    sum1 = 0
    len_list = len(list_of_numbers)
    result = 0
    # Среднее арифметическое
    for x in list_of_numbers:
        sum1+=x
    s = sum1/len_list
    # Стандартное отклонение
    for x in list_of_numbers:
        result += ((x - s)**2)
    return (result/(len_list-1))**0.5

assert std_deviation([1, 7, 9]) == 4.163331998932266
assert std_deviation([1, 1, 1, 1, 1, 1, 1]) == 0.0
assert std_deviation([10, 1, 1, 1, 1, 1]) == 3.6742346141747673
'решение зачтено'